1. Field of the Invention
The present invention relates to a monitoring system, particularly to a tire status monitoring-transmission system and a transmission device thereof.
2. Description of the Related Art
As indicated by the terminology itself, the tire pressure monitoring system (TPMS) is a system to detect tire pressure. TPMS can automatically monitor the tire status and alert the user about underpressure, overpressure, fast air leakage, overtemperature of the tires.
An underpressure tire is likely to deform, increase contact area and friction with the road, experience more abrasion, and have shorter service life and higher risk of tire bursts. According to the experimental results, 3PSI tire pressure reduction will increase over 1% gasoline consumption. An overpressure tire is likely to decrease traction ability and cause vehicle skid. Therefore, tire pressure is a critical factor for driving safety.
In addition to tire pressure, tire temperature is also an important factor for driving safety. The higher the tire temperature, the lower the tire strength, and the greater the tire deformation. Increased tire temperature will accelerate tire abrasion and decrease the service life of the tire. Therefore, appropriate tire pressure and tire temperature not only maintains driving safety but also decreases gasoline consumption and increases the service life of the tire.
As shown in FIG. 1, a conventional TPMS comprises a tire pressure monitoring device 70 installed in a wheel of a vehicle. The tire pressure monitoring device 70 includes a tire pressure monitoring unit 72. The tire pressure monitoring unit 72 further includes an angular velocity sensor 724 or a gravity sensor to detect whether the wheel is rotating. In FIG. 1, the angular velocity sensor 724 is used to exemplify the sensor for detecting wheel rotation. Once detecting that the wheel is rotating, the angular velocity sensor 724 triggers the tire pressure monitoring unit 72 to detect tire pressure and transmit the tire pressure signal to a control unit 74. The control unit 74 transmits the tire pressure signal through a wireless transmission unit 76 to an external wireless receiving device 80 matched with the wireless transmission unit 76. The tire pressure monitoring unit 72, the control unit 74 and the wireless transmission unit 76 are all powered by an energy storage unit 78. The signals can only be transmitted from the wireless transmission unit 76 to the wireless receiving device 80 unidirectionally. In the conventional technology, the wireless receiving device 80 cannot inform the wireless transmission unit 76 that the tire pressure signal has been received. Therefore, the tire pressure monitoring device 70 cannot confirm whether the tire pressure signal is received. The conventional TPMS normally transmits tire pressure signals in a Bluetooth technology. In the ordinary Bluetooth technology, the wireless transmission unit 76 and the wireless receiving device 80 must be matched before signal transmission. However, the matching process would consume a lot of time. Besides, the blind angle occurring in wheel rotation often impairs matching. Then, the system will take longer time and consume more power to complete the matching. Thus, the service life of the battery is shortened. Further, the link between the wireless transmission unit 76 and the wireless receiving device 80 will be interrupted once communication between the wireless transmission unit 76 and the wireless receiving device 80 has disappeared over 30 seconds. Thus, the wireless transmission unit 76 and the wireless receiving device 80 need re-matching for communication. The frequent matching activities further increase the power consumption.
Besides, the wireless transmission unit 76 of the tire pressure monitoring device 70 cannot directly transmit signals to a wireless communication device. If the tire pressure signal is intended to be transmitted to a wireless communication device, the wireless receiving device 80 must further have the configuration shown in FIG. 2. In FIG. 2, the wireless receiving device 80 includes a wireless receiving unit 82, a control unit 84 and a wireless transmission unit 86. After the wireless receiving unit 82 receives the tire pressure signal, the control unit 84 controls the wireless transmission unit 86 to transmit the tire pressure signal to a portable wireless communication device 90.
The abovementioned conventional technology uses the angular velocity sensor 724 to detect whether the wheel is rotating. However, the angular velocity sensor is more likely to break down. Moreover, the angular velocity sensor cannot detect vehicle movement unless the velocity of the vehicle exceeds 30 Km/hr. therefore, the angular velocity sensor also consume much power.
Accordingly, the present invention proposes a tire status monitoring-transmission system and a transmission device thereof to overcome the conventional problems.